All metal miniature airplane



Jan. 10, 1939. A. B. CAPRINE I ALL METAL MINIATURE AIRPLANE Filed May 16, 1958 Patented Jan. 10, 1939 STATES PATENT ()FFICE 4 Claims.

My invention relates to a miniature airplane manufactured from standard sheet aluminum or duralumin, without preforming or struck-up die methods, of which the following is a specificatio" i is a perspective View of the entire airplane, showing the basic principles of the idea, excluding the engine mount and landing gear. These, when added, will be conventional type. Dotted lines show points of prefolding.

2 is a detailed construction of one-half of the horizontal stabilizer. Dotted lines show points of preiolding.

3 is a fragmentary view of the airplane another way in which the wings may be ently attached to the fuselage.

ieiiy, the invention consists in making a miniature airplane, from sheet aluminum, or duralumin, and more specifically in making it from four principal pieces of metal, described as follows:

A flat piece of very light aluminum, or duralumin, is out (to the dotted line shape) I, Fig. i, then, edges 2-2, are bent down as shown. This sheet is then hand bent upward until the edges 2--2, come together, forming a hollow fuselage 3, without preforming by stampings or dies. This fuselage may also be bent to have a circular section, or an angular or diamond shape section, as alternate design. A cap strip li of heavier and stifier metal is folded so as to have a U shaped cross section and is then slipped over the two joining edges 2 2, clamped tightly, and riveted, or spot welded where necessary; forming a very strong back bone, to which are attached all the principal lifting and stressing members. Particular emphasis is placed on the importance of this cap strip of heavier and harder metal, which forms a very strong stiffener with four thicknesses of metal, to which all the strains are applied.

Bulk heads 5--5' are then installed, having connected between them a tie bar 6, of thin spring steel material, having two vertical tongues, 6'--t", extending up thru the cap strip on the top of the fuselage intended to receive thru slots 5-4 the mounting of the wing in a flexible manner, that will allow the wing to move up and down laterally when buffeted by a Wind current, without disturbing the equilibrium of the entire plane.

An alternate for the spring steel fiat tie bar and tongue assembly 6-6" may be made by substituting a U shaped spring wire 19 extending up thru the top cap strip similar to the tongues, and the wing, said wing having a hole thru which the ends of the spring wires pass, thus permitting the same movement of the wing laterally, as shown in Fig. 3 as a means of adding more strength I may incorporate laterally extending springs 58 connecting on outer point of the wing to the fuselage.

Shear pins, 8-8, of very soft metal are inserted into holes of the spring steel tongues protruding thru the top of the wing. The soft material of the pins is intended to allow the wing to shear them off, in case of a bad landing, thereby preventing damage to the wing, which is very common to the present art.

The vertical rudder is formed by an operation similar to the one which forms the fuselage, and is likewise reinforced.

The monoplanewing is formed by a similar flat piece of very light gauge aluminum, or duralumin 9, (as shown in dotted line), out to the exact span of the wing, and to the width of the combined length of the upper and lower camber of the wing rib, plus a quarter inch for the seam, then bent as shown in dotted line 10.

Ribs H-H'-H" are then inserted in the ends and in the center, and the seam clamped closed, as in i2, completing a very satisfactory full cantilever metal wing, without spars and a minimum of intermediate ribs, 100% skin stressed.

The horizontal stabilizers are next formed by taking a fiat square piece of the same metal l3, Fig. 2 (shown in dotted line) and folding it along its diagonal axis, and along the seam 14, after which is inserted the main rib l5, and the seam clamped down tightly, completing one side of the stabilizer. The other side is similarly constructed. They are then mounted on the fuselage with the two screws |l6' passing thru the vertical rudder which is an integral part of the fuselage, and bolted together with the nuts |7-ll. These nuts being accessable thru a small inspection window under the right hand half of the stabilizer.

Two coil springs, ill-48 Fig. 3 may be attached between the fuselage and wing on both sides of the wing to augment the efiectiveness of the flexible spring mounting of the wing, it necessary.

Having set forth the above description, I claim:

1. A fuselage of a miniature airplane, constructed from a single piece of sheet material having a longitudinal sheet material stiffener to which is attached the lifting wing.

2. The elements of claim 1 with the additions that the wing is resiliently mounted on the sheet material stiffener.

3. The elements of claim 1 wherein the sheet material is sheet aluminum or alloy thereof.

4. The elements of claim 1 wherein the sheet material stiffener is in the form of a U shaped sheet material clamp which fastens the edges of the sheet material fuselage together.

ALIXANDER A. CAPRINE. 

